The present invention relates to cooling arrangements for use within gas turbine engines.
A conventional gas turbine engine incorporates many components which are exposed to the heat of combustion during operation, and which require cooling in order for the engine to perform properly.
The present invention provides a cooling arrangement for a gas turbine engine, the arrangement comprising at least one passage providing a path for cooling air from a cooling air supply and through at least one component of the engine, and valve means in the path and operable to modulate the flow of cooling air along the path, the valve means being located downstream of at least one location which is cooled, in use, by the cooling air.
The valve may be located at the downstream end of that part of the path which passes through the said component. The valve may be located downstream of the said component. Preferably the path passes through a plurality of engine components, the valve means being located downstream of at least one of the components. Preferably the path passes consecutively through a plurality of engine components.
The components may include at least one fixed component, such as a nozzle guide vane or shroud segment. The components may include at least one movable component, such as a fan blade, compressor blade or turbine blade. The path may extend through a shaft by which the movable component is carried, and may extend generally radially between the shaft and the movable component.
Spurs may be provided from the path, to provide cooling air to positive pressure seals.
Preferably the valve means, when opened, allows cooling air to discharge from the downstream end of the path into the combustion gas stream of the engine.